1. [intransitive and transitive] to try to find out the truth about something such as a crime, accident, or scientific problem: The state police are investigating the incident. The study investigates the impact of violent TV programming on children. I heard a noise and went downstairs to investigate.

REGISTERIn everyday English, people often say look into something rather than investigate something:I’ll ask my colleague to look into it.

2. [transitive] to try to find out more about someone’s character, actions etc, because you think they may have been involved in a crime: Penney was already being investigated by the police on suspicion of murder.

investigate verb ADV. carefully, closely | extensively | fully, properly, thoroughly The allegations have not yet been properly investigated. further | actively VERB + INVESTIGATE ask sb to, be called in to Police have been called in to investigate the complaints. agree to, pledge to, promise to The company has pledged to investigate claims that its products are unsafe. aim to, be designed to, seek to